From 90805175a206f784b6a77f16f07b07f6803e286b Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Mon, 14 Mar 2022 11:20:41 -0700 Subject: bpf: Adjust BPF stack helper functions to accommodate skip > 0 commit ee2a098851bfbe8bcdd964c0121f4246f00ff41e upstream. Let's say that the caller has storage for num_elem stack frames. Then, the BPF stack helper functions walk the stack for only num_elem frames. This means that if skip > 0, one keeps only 'num_elem - skip' frames. This is because it sets init_nr in the perf_callchain_entry to the end of the buffer to save num_elem entries only. I believe it was because the perf callchain code unwound the stack frames until it reached the global max size (sysctl_perf_event_max_stack). However it now has perf_callchain_entry_ctx.max_stack to limit the iteration locally. This simplifies the code to handle init_nr in the BPF callstack entries and removes the confusion with the perf_event's __PERF_SAMPLE_CALLCHAIN_EARLY which sets init_nr to 0. Also change the comment on bpf_get_stack() in the header file to be more explicit what the return value means. Fixes: c195651e565a ("bpf: add bpf_get_stack helper") Signed-off-by: Namhyung Kim Signed-off-by: Alexei Starovoitov Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/30a7b5d5-6726-1cc2-eaee-8da2828a9a9c@oracle.com Link: https://lore.kernel.org/bpf/20220314182042.71025-1-namhyung@kernel.org Signed-off-by: Greg Kroah-Hartman Based-on-patch-by: Eugene Loh --- include/uapi/linux/bpf.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/uapi/linux/bpf.h') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 762bf87c26a3..baa2867dc236 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2163,8 +2163,8 @@ union bpf_attr { * * # sysctl kernel.perf_event_max_stack= * Return - * A non-negative value equal to or less than *size* on success, - * or a negative error in case of failure. + * The non-negative copied *buf* length equal to or less than + * *size* on success, or a negative error in case of failure. * * long bpf_skb_load_bytes_relative(const void *skb, u32 offset, void *to, u32 len, u32 start_header) * Description @@ -3448,8 +3448,8 @@ union bpf_attr { * * # sysctl kernel.perf_event_max_stack= * Return - * A non-negative value equal to or less than *size* on success, - * or a negative error in case of failure. + * The non-negative copied *buf* length equal to or less than + * *size* on success, or a negative error in case of failure. * * long bpf_load_hdr_opt(struct bpf_sock_ops *skops, void *searchby_res, u32 len, u64 flags) * Description -- cgit v1.2.3 From 73f2f37417b035d9607888be4fd23a9e709a85c6 Mon Sep 17 00:00:00 2001 From: Hengqi Chen Date: Thu, 10 Mar 2022 23:53:35 +0800 Subject: bpf: Fix comment for helper bpf_current_task_under_cgroup() commit 58617014405ad5c9f94f464444f4972dabb71ca7 upstream. Fix the descriptions of the return values of helper bpf_current_task_under_cgroup(). Fixes: c6b5fb8690fa ("bpf: add documentation for eBPF helpers (42-50)") Signed-off-by: Hengqi Chen Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20220310155335.1278783-1-hengqi.chen@gmail.com Signed-off-by: Greg Kroah-Hartman --- include/uapi/linux/bpf.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/uapi/linux/bpf.h') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index baa2867dc236..b43a86d05494 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1490,8 +1490,8 @@ union bpf_attr { * Return * The return value depends on the result of the test, and can be: * - * * 0, if current task belongs to the cgroup2. - * * 1, if current task does not belong to the cgroup2. + * * 1, if current task belongs to the cgroup2. + * * 0, if current task does not belong to the cgroup2. * * A negative error code, if an error occurred. * * long bpf_skb_change_tail(struct sk_buff *skb, u32 len, u64 flags) -- cgit v1.2.3 From 995f517888687c0730bc3d2dbca424c27350eaa7 Mon Sep 17 00:00:00 2001 From: Jakub Sitnicki Date: Sun, 30 Jan 2022 12:55:17 +0100 Subject: bpf: Make dst_port field in struct bpf_sock 16-bit wide [ Upstream commit 4421a582718ab81608d8486734c18083b822390d ] Menglong Dong reports that the documentation for the dst_port field in struct bpf_sock is inaccurate and confusing. From the BPF program PoV, the field is a zero-padded 16-bit integer in network byte order. The value appears to the BPF user as if laid out in memory as so: offsetof(struct bpf_sock, dst_port) + 0 + 8 +16 0x00 +24 0x00 32-, 16-, and 8-bit wide loads from the field are all allowed, but only if the offset into the field is 0. 32-bit wide loads from dst_port are especially confusing. The loaded value, after converting to host byte order with bpf_ntohl(dst_port), contains the port number in the upper 16-bits. Remove the confusion by splitting the field into two 16-bit fields. For backward compatibility, allow 32-bit wide loads from offsetof(struct bpf_sock, dst_port). While at it, allow loads 8-bit loads at offset [0] and [1] from dst_port. Reported-by: Menglong Dong Signed-off-by: Jakub Sitnicki Link: https://lore.kernel.org/r/20220130115518.213259-2-jakub@cloudflare.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- include/uapi/linux/bpf.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/uapi/linux/bpf.h') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index b43a86d05494..0f39fdcb2273 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4180,7 +4180,8 @@ struct bpf_sock { __u32 src_ip4; __u32 src_ip6[4]; __u32 src_port; /* host byte order */ - __u32 dst_port; /* network byte order */ + __be16 dst_port; /* network byte order */ + __u16 :16; /* zero padding */ __u32 dst_ip4; __u32 dst_ip6[4]; __u32 state; -- cgit v1.2.3